If we take a differential of Imaginary unit, dI ,which is imaginary infinitesimal (also mentioned by prof. Bell as i*epsilon):

1) What would be its orientation relative to I ? ( most likely 90 degrees )
2) In which space we would see this orientation?
3) If multiplying by I means rotation by 90 degress in complex plane, would multiplying by dI mean infinitesimal rotation in what plane?
4) What is self root of dI? Or what tetration would result in dI?